Nitric oxide and peroxynitrite-mediated pulmonary cell death.
Nitric oxide (.NO) can be produced within the lung, and recently inhaled nitric oxide has been used as a therapeutic agent. Peroxynitrite1 (ONOO-), the product of the nearly diffusion-limited reaction between .NO and superoxide, may represent the proximal reactive species mediating .NO injury to pulmonary cells. To investigate the physiological and pathological reactivities of .NO and ONOO- at the molecular and cellular levels, bovine pulmonary artery endothelial cells (BPAEC) and rat type II epithelial cells were exposed to .NO (0.01-2.5 microM/min for 2 h) generated by spermine-NONOate and papa-NONOate and to the same fluxes of ONOO- generated by 1,3-morpholinosydnonimine (SIN-1). Exposure to SIN-1 resulted in cellular injury and death in both cell types. Epithelial cells displayed a concentration-dependent loss of cellular viability within 8 h of exposure. In contrast, BPAEC loss of cellular viability was evident after 18 h postexposure. Events preceding cell death in BPAEC include depolarization of the mitochondrial membrane, evident as early as 6 h postexposure, loss of cellular redox activity at 16 h, and DNA fragmentation detected by in situ staining at 18 h after exposure. Exposure of BPAEC to .NO did not affect the cellular viability, but type II cells were injured in a manner similar to ONOO- exposure. .NO-mediated cellular injury within type II cells was reduced by preincubation with N-acetylcysteine. The data imply that the pathological and physiological effects of .NO may be regulated by its reactions with superoxide and reduced thiols.
Gow
A J
AJ
Institute for Environmental Medicine, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA.
Thom
S R
SR
Ischiropoulos
H
H
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009566:Nitrates / Q000494:pharmacology*; D009569:Nitric Oxide / Q000494:pharmacology*; D009589:Nitrogen Oxides; D016877:Oxidants / Q000494:pharmacology; D011651:Pulmonary Artery; D051381:Rats; D017207:Rats, Sprague-Dawley; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology
D009566:Nitrates; D009589:Nitrogen Oxides; D016877:Oxidants; C091861:spermine nitric oxide complex; C039642:peroxynitric acid; D013096:Spermine; D009569:Nitric Oxide; C002385:linsidomine; D008981:Molsidomine; D000111:Acetylcysteine